Apparatus for shuttling a test element from a discharge path to a wash station

ABSTRACT

There are disclosed a shuttle apparatus and method for catching a test element ejected from an incubator, for carrying it to a station outside the incubator, e.g., a wash station, and for returning it to a loading station. Preferably, the apparatus comprises a simplified catcher plate and means for moving the plate in an arcuate path around a portion of the circumference of the incubator. The plate cooperates with stop means disposed above said arcuate path, to capture a washed element upon reloading, so that the washed element can be reloaded by returning it to the original path used to load elements into the incubator in the first instance.

This is a division of application Ser. No. 615,530, filed Nov. 19, 1990now U.S. Pat. No. 5,179,960.

FIELD OF THE INVENTION

The invention relates to an analyzer for ascertaining analyteconcentrations in body liquids dispensed onto test elements,particularly such analyzers that need a wash station to allowimmunoassays to be conducted.

BACKGROUND OF THE INVENTION

Analyzer mechanisms have been provided for receiving slide test elementsfrom incubators, to carry them on to additional stations, e.g., a washstation. Such a mechanism is described in U.S. Pat. No. 4,857,471.Although this mechanism functions admirably, it uses a platform thatlowers into the "dump" path of the ejected slide element to catch theslide element, FIG. 2. The platform cannot move on to the wash stationbut provides a stationary support. As a result, a claw must then be usedto transfer the slide element from this stationary support to a movabletrain 104. Thus, the noted mechanism does have the disadvantage ofrequiring a transfer claw and means other than the catching surface tomove the slide element to the wash station. Furthermore, the train thatis used for the wash step transfer is of substantial size andcomplexity.

Thus, prior to this invention, there has been a need for an improvedtransfer mechanism off-line of the incubator, to allow a slide elementto be removed from the incubator, washed and reinserted, using simplerand less expensive parts.

SUMMARY OF THE INVENTION

We have constructed a shuttle mechanism and method that solve theaforesaid problems, with a catcher plate that provides the neededmovement of a "caught" test element ejected from an incubator, to a washstation and back into a loading station for reinsertion into theincubator. Further, the catcher plate is constructed to provide otherimportant features, all in one simplified piece.

More specifically, in accord with one aspect of the invention, there isprovided an analyzer having processing stations including an incubatorand a wash station outside of said incubator, means for ejecting a testelement from one of the processing stations, and means defining adischarge path to carry the ejected element out of the analyzer. Theanalyzer is improved in that it further includes a catcher plate forcatching test elements ejected from the one processing station by theejecting means, and means for moving the plate into a position in thedischarge path to intercept an ejected element moving along the path,the moving means including means defining a track constructed to movethe catcher plate and an intercepted test element from the path to thewash station.

In accord with another aspect of the invention, there is provided ananalyzer comprising processing stations including an incubator, meansfor injecting a test element bearing a sample liquid along a first pathinto one of the processing stations, means for ejecting a test elementfrom the one station, and discharge means defining a second path forcarrying an ejected test element away from the one station. The analyzeris improved in that it further includes a stop mechanism between thefirst path and the second path, the mechanism including a) a shoulderadjacent the first path to prevent a test element on the first path frommoving off the first path towards the second path, and b) a cammingsurface under and adjacent to the stop shoulder, the camming surfacebeing shaped to cause the stop mechanism to ride up over a test elementmoved from the vicinity of the second path to the first path, so that atest element can be moved only from the second path to the first path,and not from the first path to the second path.

In accord with yet another aspect of the invention, there is provided atest element support for use in an analyzer that analyzes analytes of abody liquid contained in a test element, the support comprising a platehaving a frame, a central portion within and flexibly secured to theframe, and raised shoulders on opposite edges of the frame dimensionedto retain a test element between the shoulders to prevent a held elementfrom being displaced off the support, the central portion beingcantilevered from the frame at only one side thereof, so as to becapable of flexing in and out of the plane of the frame.

In accord with still another aspect of the invention, there is provideda method of washing an incubated test element and comprising the stepsof loading a test element at a first station into an incubator, ejectingat a second station a loaded test element from the incubator, catchingthe ejected test element, shuttling the caught element to a washstation, washing the shuttled test element at the wash station, andreturning the washed element to the incubator. The method is improved inthat the returning step comprises moving the washed element back to thefirst station, and reloading it into the incubator.

Accordingly, it is an advantageous feature of this invention that thesame means that catches a test element ejected from the incubator, isused to transport such test element to a wash station.

It is a related advantageous feature of the invention that the means fortransporting a test element from its ejected location to an additionalstation, is simplified.

It is another advantageous feature of the invention that a removed andwashed test element is returned to the original loading mechanism, forreloading into the incubator, to avoid the use of a separate loader.

Other advantageous features will become apparent upon reference to thefollowing Description of the Preferred Embodiments, when read in lightof the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic, plan view of an analyzer constructed inaccordance with the invention;

FIG. 2 is a fragmentary perspective view showing especially the shuttleapparatus of the invention outside the incubator;

FIG. 3 is a fragmentary side elevational view taken generally along theline III--III of FIG. 1;

FIG. 4 is a perspective view of the catcher plate that reciprocateswithin the shuttle apparatus of FIG. 2;

FIG. 5 is a plan view of the catcher plate of FIG. 4, showing in phantoma test element E carried by it;

FIG. 6 is a fragmentary, partially schematic (for element E) sectionview taken generally along the line VI--VI of FIG. 5;

FIG. 7 is a fragmentary plan view of the shuttle apparatus of FIG. 3;

FIGS. 8 and 9 are section views taken generally along the linesVIII--VIII and IX--IX of FIG. 7, respectively; and

FIGS. 10, 11, 12 and 13A-13C are fragmentary section views takengenerally along the line Q--Q of FIG. 7, illustrating the sequentialoperation of the shuttle apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention is hereinafter described in connection with the preferredembodiments, in which the transfer mechanism that catches and transfersslide-like test elements is disposed outside of an incubatorparticularly positioned in an analyzer, to transfer the test element toa wash station and back to the incubator, and in which the test elementsare of a type similar to those obtained from Eastman Kodak Company underthe trademark "Ektachem" slides, or from Fuji Photo under the tradename"Drychem". In addition, such a transfer mechanism is useful adjacent anyprocessing station of an analyzer, whether or not it is the incubatorand regardless of the position of that station, to take the slide-liketest element to any other processing station and back to the firstprocessing station from which the test element is received. Stillfurther, such a transfer mechanism is useful regardless of theconstruction of the test element, although generally planar elements arepreferred since the transfer mechanism is shaped preferably to handlesuch planar elements.

An analyzer 10 in which this shuttle invention is useful comprises, FIG.1, preferably a station 20 for loading a slide-like test element E intoa sample dispensing station 30, and for loading such an element, alongpath 32, now bearing patient sample, into an incubator 40. Preferably,loading station 20 includes a pusher blade 22 that pushes an element Ealong path 29 so as to be injected into station 30. The loading stationincludes tip locator 34, FIG. 2, with two apertures 36,37 as isconventional for patient sample metering, and an aperture 38 forreference liquid metering, as is also conventional. Also preferably, theincubator is the rotating type, arrow 42 and includes a reflectometer50, FIG. 1, for scanning colorimetric test elements while they are heldat a plurality of stations 44, etc., FIG. 2, as defined by a rotor 46.Such an analyzer includes an electrometer 52, FIG. 1, for readingpotentiometric test elements after they are removed from the incubatorby, e.g., a pusher blade 48, FIG. 2. A wide variety of incubators isuseful for this purpose, for example, that shown in, e.g., U.S. Pat. No.4,935,374.

Similar to the construction of the analyzer in U.S. Pat. No. 4,857,471,a wash station 70 is disposed outside of incubator 40, displacedcircumferentially from station 30. The wash station comprises a boss 72and aperture 74 that serve to hold a dispensing tip in properorientation with respect to a test element to be washed. In betweenstations 30 and 70 is an eject station 80, including a discharge pathdefined by aperture 82, FIG. 1, into which a test element is ejected,arrow 84, when its readings are completed. Shuttle apparatus is thenprovided to allow test elements to be intercepted at station 80, takento wash station 70, and reinserted into the incubator, as in the '471patent. In accord with one aspect of the invention, it is theimprovement of this apparatus to which the invention is addressed.

More specifically, the shuttle apparatus 100, FIG. 2, comprises acatcher plate 110, means 160 for supporting plate 110 for movement alonga path 112, FIG. 1 that is preferably curvilinear, and means 140, FIG.2, for driving plate 110 along path 112, FIG. 1. Importantly, path 112is constructed to extend back to station 30 to intersect path 32, sothat a test element washed at station 70 can be reinserted into theloading path 32.

Referring now to FIGS. 4-6, catcher plate 110 comprises a frame 120shaped to hold a test element E, shown in phantom. Accordingly, frame120 is generally rectangular, and is provided with two opposed shoulders122,124 shaped and positioned, FIG. 6, to restrain element E from movingoff plate 110 as the latter moves on path 112, FIG. 4. Shoulder 122 isthe leading shoulder and is preferably beveled, to allow shoulder 122 tocam under element E when the latter is returned to and retained at path32, FIG. 1, as described hereinafter.

A central support member 128 is flexibly connected to frame 120, FIG. 4,to do the principal carrying of element E. The flexibility is achievedby reason of the cantilever connection of support member 128 at one side130 of frame 120. As a result, member 128 is able to flex relative toframe 120, in and out of the plane defined by frame 120.

Plate 110 is preferably integrally connected to a drive tongue 132 thatextends along a curvilinear arc that matches the curve of means 160 andpath 112. The outside edge of tongue 132 has a raised ridge 134 providedwith means, such as slots 136, to cooperate with a sensor. The insideedge 138 of tongue 132 comprises a raised ridge that is provided with arack 139. Rack 139 is driven by gear 142 of drive means 140, FIG. 2.

Support means 160 for plate 110 and its tongue 132 comprises two opposedtrack members 162 and 164, FIGS. 7-9, between which plate 110 and tongue132 reciprocate. Members 162 and 164 preferably have the same arcuatecurvature as tongue 132. Most preferably, member 162 is generally flat,FIG. 8, and is apertured at 82 for element discharge, and at 166 toreceive drive gear 142, FIG. 7. Opposed track member 164 is rail-shapedat 170, 172 to accommodate ridge 134, and rack 139 of tongue 132, FIG.8. Member 164 is secured to lower member 162 at bottom portions 174 and176. Member 164 is apertured to accommodate gear 142, and further at 74,FIGS. 1 and 2, to provide for wash station 70.

In another aspect of the invention, there is provided stop means 180that allow a washed test element to be returned and retained at station30, FIG. 7. For this purpose, stop means 180 is disposed adjacent theinjection path 29,32, at the intersection location of that path withpath 112. Most preferably, stop means 180 comprise a flexure plate 182,FIGS. 2 and 7, that is cantilevered by arm 184 from the rest of uppermember 164. The outer edge 186 of plate 182 provides a shoulder againstwhich a test element abuts, when it moves along path 29,32. In addition,flexure plate 182 includes on its undersurface 189, FIG. 9, one andpreferably two camming feet 190, 192, FIGS. 7 and 9, which allow plate182 to ride up over a test element, FIG. 12, being moved by plate 110 onpath 112 to path 29, 32.

Optionally, a viewing port 196 can be provided, FIG. 4, adjacent station30, to allow a wetness detector to scan a slide element as liquid isdispensed thereon.

The apparatus of the invention further includes bias means 200 atstation 30, FIG. 3, and locating surfaces 210, 212, FIG. 11, at washstation 70. In station 30, the bias means 200 acts to bias a testelement up against the tip locator 34 at station 30. Means 200 comprisea platen 202 that is beveled at 203, FIG. 12, and a spring 204 exertingan upward force F, arrow 206, FIG. 3. Entrance slot 208 allows a testelement to be inserted into station 30 and onto either platen 202 orshuttle plate 110, as shown in FIG. 3.

At station 70, FIG. 11, stop surface 210 is provided to stop themovement of a test element E' even as plate 110 continues to advanceslightly further, arrow 112. Undersurface 212 at station 70 is theceiling against which element E' is pushed by flexible support member128. An opposite depression 220 is formed in lower track member 162 toreceive frame 120 of plate 110, that is cammed downwardly due to cammingsurface 122 of frame 120 pressing against element E'. In addition, acamming surface, not shown, extending diagonally from surface 210ensures proper location of element E' in the direction out of the planeof FIG. 11.

The wash method will be readily apparent from the previous description.In brief, plate 110 is moved by drive means 140 into position so as tointercept an ejected test element E', FIG. 10, thus preventing elementE' from falling out discharge aperture 82.

Next, plate 110 moves along path 112 due to the action of drive means140, until element E' is at wash station 70, FIG. 11. A suitablepipette, not shown, is inserted into aperture 74, and boss 72 serves tohold the pipette the proper distance within station 70. At the sametime, plate 110 pulls element E' up against stop shoulder 210 and theflexure of support member 128 is such as to push element E' up againstundersurface 212 of station 70. The proper spacing of the pipette andelement E' is now defined, which can be, e.g., about 1.3 mm. About 10 μLof wash liquid is preferably ejected onto the element E', preferably ata rate of about 0.5 μL per second, for 20 seconds. However, other ratescan also be used, depending on the hydrophilicity of the element beingwashed.

After washing, plate 110 is now returned towards station 30 and awayfrom station 70, by reversing the direction of rotation of gear 142.

In accord with another aspect of the invention, the wash method differsfrom that previously used in that the washed element is returned to thestation from which elements that have just received sample are loadedinto the incubator. This allows the analyzer to be simplified in thatthe same pusher blade used to initially load the element into theanalyzer, is reused to re-load the element. More specifically, as plate110 and element E' move from the vicinity of discharge path 82 intostation 30 where path 112 intersects path 29,32, FIG. 12, cammingsurfaces 190 and 192 allow stop means flexure plate 182 to ride up overelement E'. At the same time, platen 202 is cammed downwardly, due tothe camming action caused by surface 203.

Once element E' is returned to station 30, FIGS. 13A-13C, stop means 180is effective to restrain element E' from leaving station 30 with plate110. That is, shoulder 186 slips behind element E', FIG. 13A, and camsurface 193 allows plate 110 to slip under element E', so that as plate110 starts moving out of station 30 along the path of arrow 112, FIG.13B, shoulder 186 holds element E' from following plate 110. Plate 110is carefully advanced into the position shown in FIG. 13A, by drivemeans 140, to ensure element E' is advanced past shoulder 186. The stepsof travel of means 140 can be adjusted to ensure that this advanceoccurs. Meanwhile, platen 202 is pushed up by its spring 204, to furtherhold element E'. That is, plate 110 pushes element E' up due to theupward force of the platen. When plate 110 is completely withdrawn, FIG.13C, element E' is positioned for reloading into incubator 40, usingpusher blade 22. (The positioning of the parts in FIG. 13C is also theirposition when an element is first loaded into station 30 for dispensingpatient sample and/or reference liquid via apertures 36, 37 and 38, ofwhich 38 is not shown.)

A bumper spring 300 is preferably included, FIG. 13A, against whichplate 110 pushes when element E' is being returned to station 30. Thisspring prevents over-travel of plate 110, but primarily it assists inholding test elements against stop shoulder 186, FIG. 13B.

Following reloading of the washed slide into the incubator, which occursafter the events illustrated in FIG. 13C, further incubation and areading of the element occur. When a read element is ready for disposal,ejection occurs using pusher blade 48, arrow 310, FIG. 2, except thistime, plate 110 is not in position at station 80 to catch the element.Instead, it falls through aperture 82, FIG. 1, into a suitable disposalcontainer.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

What is claimed is:
 1. In an analyzer comprising at least one processingstation including an incubator, means for injecting a test elementbearing a sample liquid along a first path into one of said processingstations, means for ejecting a test element from said one station, anddischarge means defining a second path for carrying an ejected testelement away from said one station,the improvement wherein said analyzerfurther includes a stop mechanism between said first path and saidsecond path, said mechanism including a) a stop shoulder adjacent saidfirst path to prevent a test element on said first path from moving offsaid first path towards said second path, and b) a camming surface underand adjacent to said stop shoulder, said camming surface being shaped tocause said stop mechanism to ride up over a test element moved from aportion of said second path to said first path, so that a test elementcan be moved from said portion of second path to said first path, butnot from said first path to said portion of second path.
 2. An analyzeras defined in claim 1, wherein said one processing station comprisessaid incubator.
 3. An analyzer as defined in claim 1 or 2, and furtherincluding a wash station, track-defining means extending from saidsecond path to said wash station and then to said first path, and movingmeans for moving a test element along said track-defining means.
 4. Ananalyzer as defined in claim 3, wherein said moving means comprise aframe having opposed, raised shoulders dimensioned to retain a testelement between said shoulders to prevent a held element from beingundesirably displaced off said moving means.
 5. An analyzer as definedin claim 4, and further including in said moving means a central supportmember disposed between said shoulders, said member being flexiblyconnected to said frame to allow relative flexing between said supportmember and said frame in and out of the plane of said frame.
 6. Ananalyzer as defined in claim 5, wherein said support member iscantilevered from said frame at only one side thereof, so as to becapable of flexing in and out of the plane of said frame.
 7. An analyzeras defined in claim 5, wherein said shoulders are disposed on theleading and trailing edges, respectively, of said moving means as itmoves along said track-defining means from said wash station, saidleading edge shoulder being provided with a shoulder cam surface slopedsufficiently to allow said support member to ride under a test elementthat is on said support member when said test element is held frommovement along said track-defining means by said stop mechanism.